• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2147-2155
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• 2022

Nuclear safety-related underground liquid storage tanks, such as those used to store fuel for emergency diesel generators, are critical components for safety of hundreds of existing nuclear power plants (NPP) worldwide. Since most of those NPP will continue to operate for decades, a beyond design base (BDB) seismic screening of safety-related underground tanks in those NPP is beneficial and essential to public safety. The analytical methodology for buried tank subjected to seismic effect, including a BDB seismic evaluation, needs to consider both soil-structure and fluid-structure interaction effects. Comprehensive analysis of such a soil-structure-fluid system is costly and time consuming, often subjected to availability of state-of-art finite element tools. Simple, but practically and reasonably accurate techniques for seismic evaluation of underground liquid storage tanks have not been established. In this study, a mechanics based solution is proposed for the evaluation of a cylindrical underground liquid storage tank using hand calculation methods. For validation, a practical example of two underground diesel fuel tanks in an existing nuclear power plant is presented and application of the proposed method is confirmed by using published results of the computer-aided System for Analysis of Soil Structural Interaction (SASSI). The proposed approach provides an easy to use tool for BDB seismic assessment prior to making decision of applying more costly technique by owner of the nuclear facility.

• International Journal of Aerospace System Engineering
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• 제3권1호
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• pp.17-20
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• 2016

In this work, a structural design on horizontal axis wind turbine blade using natural flax fiber composite is performed. The structural design results of flax/epoxy composite blade are compared with the design results of glass/epoxy composite blade. In order to evaluate the structural design of the composite blade, the structural analysis was performed by the finite element method. Through the structural analyses, it is confirmed that the designed blade using natural composite is acceptable for structural safety, blade tip deflection, structural stability, resonance possibility, and weight. Finally, structural test of manufactured blade was performed. Through the structural test, it is confirmed that the designed blade is acceptable.

• 한국구조물진단유지관리공학회 논문집
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• 제22권4호
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• pp.27-36
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• 2018

현재 적용되고 있는 평가체계는 1996년 개정되어 이후 4차례 개정을 실시하였으나, 구조적 안전성의 확보 목표에 국한된 평가체계로 인해 장기적 관점의 성능저하 예측 및 예산투입을 위한 우선순위 의사결정의 근거로 활용하기에는 부족하다. 따라서, 본 연구에서는 델파이 기법과 AHP기법을 활용하여 기존 도로터널의 여러 구조형식 중 재래식(ASSM) 터널의 성능평가에 적합한 평가체계를 새롭게 제시하고자 한다. 국 내외의 기존 평가체계 및 평가항목을 검토한 결과, 도출가능한 평가항목이 한정적인 것으로 판단되어 기존에 적용되고 있는 항목에 대한 폐쇄적인 설문과 새로운 항목 도출을 위한 개방형 설문을 병행하여 설문조사를 실시하였다. 조사한 설문결과를 내용타당도 검증을 거쳐 재래식(ASSM)터널에 적합한 성능평가인자를 도출하였으며, AHP기법을 활용하여 도출된 평가항목에 대한 가중치를 산정한 후 구조물의 특성에 맞는 성능평가 체계를 새롭게 제시하여, 향후 성능평가 세부지침 수정 및 보완 시 참고자료로 활용될 수 있도록 하고자 한다.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.950-956
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• 2014

Special purpose sensor design using MEMS (Micro-Electro-Mechanical Systems) technique is commonly used in Nondestructive Testing (NDT) research for the evaluation of existing structures and for the safety control and requirements. Various sensors and network have been developed for general infrastructures as well as safety-critical applications, e.g., aerospace, defense, and nuclear system, etc. In this paper, one of sensor technique using Fiber Bragg Gratings (FBG) and Finite Element Method (FEM) evaluation is discussed. The experimental setup and data collection technique is also demonstrated. The factors influencing test result and the advantages/limitations of this technique are also reviewed using various methods.

• 한국구조물진단유지관리공학회 논문집
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• 제23권4호
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• pp.1-7
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• 2019

국가 주요 시설물의 안전점검 업무가 일원화됨에 따라 업무 효율성과 전문성 강화 등의 효과가 기대되고 있다. 세계적으로 시설물의 물리적 기능적 결함을 초기에 발견하는 외관조사의 중요성이 강조되고 있다. 이에 본 연구에서는 기존 외관조사 방법의 문제와 한계를 극복하기 위해 시설물 안전점검을 위한 E-PAD기반 상태평가 시스템을 개발하였다. 본 시스템은 시설개요, 작업목록, 외관조사, 결함표로 구성되어 있으며, 현장에서 외관조사망도를 다운받아 조사된 손상 및 정보를 입력하고, 평가 등급을 확인할 수 있다. 본 시스템의 검증을 위해 교량 10개소에 대한 외관조사 데이터를 입력하여 기존 안전등급을 비교하였다. 그 결과 시스템에서 산출된 안전등급과 기존 안전등급이 동일한 것으로 확인되었다. 또한 AHP기법을 통해 타당성 분석 결과 기존 방법 대비 기능 10%증가, 비용 36%감소, 가치 30%증가한 것으로 분석되었다. 따라서, 시설물 관리 수준 향상을 위해 체계적인 데이터 구축 및 정보 분석을 위한 시스템으로 기여할 것으로 기대된다.

• 한국재난정보학회 논문집
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• 제18권1호
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• pp.228-240
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• 2022

건설현장의 밀착형 안전관리를 위해 중대재해처벌법이 시행됨에 따라서 종합적 안전관리체계가 요구되고 있다. 안전관리수준평가관리는 건설기술진흥법에 따른 안전관리와 산업안전보건법에 따르는 보건위생 관리 체계와 안전경영시스템 등의 종합적 관계분석이 필요하다. 연구목적: 중대재해처벌법에 따른 안전. 보건관리의 종합적 분석 및 관계를 연구하여 보건위생관리의 안전평가수준향상에 궁극적 목적이 있다. 연구방법: 건설현장 전문가와 안전 관리자 대상으로 2차 델파이분석을 통해 설문항목의 타당성을 확인 후 구조방정식 예비모형을 통해 안전경영, 안전관리, 보건관리, 안전점검실행에 대한 잠재변인이 존재하는 회귀계수확인과 경로분석을 통해 총 효과(직접효과, 간접효과)로 매개효과를 확인하였다. 결과 및 결론: 구조모형에서는 안전관리, 보건체계, 안전경영에서 안전점검실행으로 가는 회귀계수(89%) 와 적정한 관찰변수의 람다 값이 확인되었다. 경로분석에서 보건계획수립적절성과 사후점검관리의 관계에서 보건위생을 매개하여 총 효과(.809)를 확인하였으며, 가설구조물안전성의 경로계수(.82)가 확인되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제2권2호
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• pp.162-169
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• 1998

This paper presents the application of system identification approaches for the safety assessment of RC-T type bridge based on the result of field test. For these problems, the moment of inertia of cross-sectional area and the natural frequency of bridge were used as structural parameters, the SAP90 program for the structural analysis and the SLP method for the minimum error. As a result, it is found that the proposed algorithm for this study appears applicable to real structures with reasonable complexity. It is shown that the introduction of approximate quadratic equations is more realistic and timesaving than the common methods.

• 항공우주시스템공학회지
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• 제14권6호
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• pp.18-25
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• 2020

This study investigated the structural behaviors and safety of an electro-mechanical linear actuator and a load simulator with a plate spring. The material and dimensions of the plate spring were determined by theoretically calculating the stress and torsional angle for the rating load of the actuator. Thereafter, a flexible multibody dynamics (FMBD) analysis was conducted on the linear actuator and load simulator to confirm the performance of the load simulator and acquire the reaction forces acting on the actuator and simulator. The structural safety of the linear actuator and load simulator was evaluated via finite element analysis using the aforementioned reaction forces. Consequently, the proposed linear actuator and load simulator were determined to be structurally safe; however, the safety factors for the actuation rod and the housing on the actuator were excessively high. Therefore, the weight and cost must be reduced to improve their design parameters in the future.

• 한국정밀공학회지
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• 제29권12호
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• pp.1331-1339
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• 2012

Safety valve used in LNG/LNG-FPSO ships is a high value valve, and it plays an important role in maintaining a fixed level of pressure by emitting LNG gas out of pipes in LNG piping system under the cryogenic and high-pressure condition when the pressure of the system connected with the LNG storage tank and pipes reaches over the set pressure. The structural stability is required for the inner pressure and thermal load because of the cryogenic and high-pressure condition, and a reliability of the safety valve is necessary for impact and deformation by opening the valve. But, the safety valve, which plays a key role for a safety of the transport and storage system, is depended on imports for over 90%, and in domestic production, the design of the valve is performed on the basis of experiences of the works without quantitative analysis for the inner operation characteristics and structural stability of the valve. In this study, impact velocity is calculated by theoretical analysis for obtaining the structural stability of the guide according to the impact load by opening the valve. The shape of the guide and the diaphragm for satisfying the structural stability are suggested and verified by using a thermal-structural analysis.

• 한국안전학회지
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• 제28권6호
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• pp.42-48
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• 2013

Forensic engineering is the application of engineering principles covering the investigation of constructed facilities and systems that fail to perform as intended, causing personal injury or damage to property, environmental, economy etc. In the year 2012, two collapsed accidents of the large scaffolding system in national thermal power station occurred one after another, causing many casualties. In this study, we had performed to investigate the collapsed accident of scaffolding system occurred in the a thermal power station of two accidents. First, the investigation about the collapsed accidents site had performed to understand collapsed state and structures of the scaffolding system. Second, reviewing the materials concerning about the applied weight on the scaffolding system had performed. The applied weight is sum of the weights of the 15 workers, additional materials for coating work and dispersed and loaded shot ball on the foothold etc. the applied weight that calculated exceed more three times than the safe working load. Third, we had confirmed the install state of the materials of the scaffolding system by reviewing the quantity of the materials on the manual and the real system. Last, structural analysis had performed to evaluate structural integrity of the scaffolding system using Ansys. Through a series of this processes, the definite accidents causes of the collapsed scaffolding system revealed. Through these studies, the collapse accident that may occur in the scaffolding system in thermal power station can be minimized by performing specialized and systematic investigation on the accidents in terms of Forensic engineering.